A critical phase in semiconductor processing involves handling and packaging of thin film semiconductor devices. Such semiconductor devices are manufactured by depositing a thin film expitaxial layer on a sacrificial layer on a growth substrate. The thin film layer is known as epitaxial lift-off ("ELO") film and typically includes thin film semiconductor devices which have been removed from the substrate. Because the thin film semiconductor devices are fragile and have extremely narrow dimensions, they are very difficult to handle, bond to substrates, and package. Specifically, such semiconductor devices are fragile and can crack under very small forces, making them difficult to handle. Further, the very thin nature of such semiconductor devices makes them very difficult to align with new substrates. Because high planarity is required (z-alignment), the difficult handling of thin film semiconductor devices makes x and y alignment difficult.
To alleviate such difficulties, some conventional techniques for handling thin film semiconductor devices involve isolating a thin film layer from the growth substrate without removing the growth substrate by e.g. Silicon On Insulator, or by bonding of the thin film semiconductor devices to a new substrate for packaging before removing the growth substrate. However, such techniques provide inadequate device and package performance upon removing the substrate before packaging. In addition, the required mechanical and chemical processing methods are detrimental to the package as a whole, degrading performance of devices in an entire package.
Other conventional techniques for handling thin film semiconductor devices involve individually handling the semiconductor devices after removing the growth substrate, and use of different bonding techniques such as Van der Waals or eutectic bonding. The bonding process is to provide ease of handling the thin film layers, improved thermal performance, electrical interconnection, etc. However, such techniques are unsuitable for handling the thin, fragile semiconductor devices in an efficient manner without damaging them- Further, such techniques prevent proper alignment and/or bonding of the semiconductor devices; provide inadequate bonding strength of the semiconductor devices to a new substrate or package; are not thermally compatible with desired bond processes; provide inadequate yield; provide low throughput serial handling of the semiconductor devices; prevent selection and control of individual semiconductor devices during bonding; and prevent proper control of the process such as aligning the semiconductor devices properly, achieving bonding planarity, controlling bonding force, and achieving repeatable and consistent results.
There is, therefore, a need for a repeatable process to fabricate, remove the growth substrate of, handle, and selectively bond thin film semiconductor devices to a new substrate in parallel.